Very cool image. I remember Mecha Maddness and how cool it was to see Mecha Sonic and Mecha Knuckles beating the tar out of each other. I'm glad someone thought to draw them with Mecha Sally. On a side note I always did like Mecha Sonic better then Metal Sonic, Mecha seems like more of a war machine. Kind of wish Robotnik had saved the design specs and updated his Metal Sonic designs. And while Mecha Sally looks cool I really hope she gets back to her normal orgainc self soon.
I like Mecha Sonic here. Not a fan of Sally being in the front, cause i see Sonic more of being the leader than Sally. But hey, it's your art, I would guess you like Sally in the front more, so I'm not gonna hate on it for what you like (cause then I would become a hypocrite).